[PATCH] mm: use symbolic names instead of indices for zone initialisation

Arch-independent zone-sizing is using indices instead of symbolic names to
offset within an array related to zones (max_zone_pfns).  The unintended
impact is that ZONE_DMA and ZONE_NORMAL is initialised on powerpc instead
of ZONE_DMA and ZONE_HIGHMEM when CONFIG_HIGHMEM is set.  As a result, the
the machine fails to boot but will boot with CONFIG_HIGHMEM turned off.

The following patch properly initialises the max_zone_pfns[] array and uses
symbolic names instead of indices in each architecture using
arch-independent zone-sizing.  Two users have successfully booted their
powerpcs with it (one an ibook G4).  It has also been boot tested on x86,
x86_64, ppc64 and ia64.  Please merge for 2.6.19-rc2.

Credit to Benjamin Herrenschmidt for identifying the bug and rolling the
first fix.  Additional credit to Johannes Berg and Andreas Schwab for
reporting the problem and testing on powerpc.

Signed-off-by: Mel Gorman <mel@csn.ul.ie>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 4 insertions, 3 deletions

diff --git a/arch/powerpc/mm/mem.c b/arch/powerpc/mm/mem.c
index 16fe027bbc12..d1c0758c5611 100644
--- a/arch/powerpc/mm/mem.c
+++ b/arch/powerpc/mm/mem.c
@@ -307,11 +307,12 @@ void __init paging_init(void)
                top_of_ram, total_ram);
         printk(KERN_DEBUG "Memory hole size: %ldMB\n",
                (top_of_ram - total_ram) >> 20);
+        memset(max_zone_pfns, 0, sizeof(max_zone_pfns));
 #ifdef CONFIG_HIGHMEM
-        max_zone_pfns[0] = total_lowmem >> PAGE_SHIFT;
-        max_zone_pfns[1] = top_of_ram >> PAGE_SHIFT;
+        max_zone_pfns[ZONE_DMA] = total_lowmem >> PAGE_SHIFT;
+        max_zone_pfns[ZONE_HIGHMEM] = top_of_ram >> PAGE_SHIFT;
 #else
-        max_zone_pfns[0] = top_of_ram >> PAGE_SHIFT;
+        max_zone_pfns[ZONE_DMA] = top_of_ram >> PAGE_SHIFT;
 #endif
         free_area_init_nodes(max_zone_pfns);
 }